feat: Add InferenceGraph support to models-web-app UI

[Prateekbala]

Description

Adds InferenceGraph (v1alpha1) support to models-web-app, enabling users to manage graph-based model inference workflows through the UI.

Changes

Backend:

• Added InferenceGraph CRUD endpoints (GET, POST, PUT, DELETE)
• Support for single namespace and all-namespaces queries
• Added inference_graph_gvk() helper for API version handling

Frontend:

• New InferenceGraph module with list, detail, and form components
• Added "View Graphs" button on main Endpoints page
• TypeScript types for InferenceGraph API (v1alpha1)
• Service layer integration with backend API

Features

• List InferenceGraphs across namespaces
• View graph details (nodes, routes, status)
• Create new InferenceGraphs via YAML/JSON editor
• Edit existing InferenceGraphs
• Delete InferenceGraphs with confirmation

Testing

Tested with local KServe cluster (kind) following . All CRUD operations verified with sample Sequence, Ensemble, and Splitter graphs.

Fixes #39

[juliusvonkohout]

Please never ever merge from master. Always do a proper git rebase master. Merge from master destroy the commit history.